1. Technical Field of the Invention
The present invention pertains generally to an electric connector. More specifically, the present invention pertains to a spring loaded electric connector having low and constant impedance, for connecting electrical signals.
2. Description of the Prior Art
In electrical communication devices such as radio transceivers or telephones, a universal connecting system is used for connecting between a main body and a speaker-microphone. The universal connecting system can be used also for connecting a radio transceiver to other remote devices. For example, some kind of portable radio transceiver may be changed to a car radio transceiver by connecting the portable radio to a communication device mounted in a car via such universal connecting system. Such universal connecting system, in general, comprises a male multi-connector and a female multi-connector. The male multi-connector includes a plurality of pin type connectors, and the female multi-connector includes a plurality of surface type connectors.
An example of such a conventional pin type connector is shown and generally indicated at 10, in FIG. 1. Plural pin type connectors like this are mounted together onto a mounting panel to constitute one male multi-connector. The conventional pin type connector 10 comprises, basically, a hollow cylindrical body 20, a plunger 30 contained in and projected from the body, a wire 50 attached to the body and a coil spring 40 positioned within the body (cf. FIG. 2). Pin type connector 10 is pressed against a corresponding surface type connector 60 to make electrical contact between a tip 32 of plunger 30 and surface 60. Plunger 30 can slide along body 20 and is biased by coil spring 40 toward an extended position in order to assure positive contact. An electrical current passes from surface 60 and plunger 30, through the coil spring 40, to wire 50.
However, a coil spring has high inductance because of its spiral figure and has resistance due to its wire length. These high inductance and resistance are undesirable to electric signals, especially to alternating current signals. This high inductance and resistance problem, that is, high impedance problem is very serious in transmitting high frequency signals, such as RF signals. Additionally, the inductance inherent in the coil varies depending on the coil length which is determined by the displacement of the plunger. This inductance change is a nuisance and badly affects the signal transmission through the connector.